Fluid pressure gauge



PH'B 28 936- G. FARLEY ET AL 2,038,928

FLUID PRESSURE GAUGE Filed April 6, 1955 Patented Apr. 28, 1936 UNI-TEDSTATES P'ATENT oFFicE;

FLUID PRESSURE: GAUGE:

California Application April 6, 1933, Serial Non 664,686

4 Claims.

This invention relates to improvements in pressure gauges, andrefers'specically to a gauge for measuring fluid pressures throughout arelatively wide range by the use of a plurality of springs of diierenttensionsV Which act sequentially, within asngle pressure chamber, toresist the uid pressure established therein.

The. utility, objects and advantages of our invention will be apparentfrom theaccompanying drawing and following detail description.

In the drawing, Fig. 1 is a longitudinal sectional view of a pressuregauge utilizing the concept of our invention.

Fig. 2 is a sectional view on line 2-2 of- Fig. l.

Referring in detail to the drawing, I indicates a casing of hollowconstruction which may comprise the body of the gauge. The casing I maybe constructed of metal such as aluminum, brass, steel or the like, andmay be provided. with a bore 2 which may extend from one end of thecasing to substantially the central portion thereof. A

bore 3 mayextend' from the opposite end of. the.

casing and may connect into the bore 2, the bore 3 being'of` lesserdiameter than bore 2'.

A cylindrical: tube 4 may be positioned within bore tl and maybefrictionallymaintained thereiin. An end I", of' the tube 1I mayIprotrude from the end ofthe casing I andmay be provided withV screwthreads 6 whereby fitting Iv maybe threadedly-` engaged. The end of'fitting 'I- may terminate in the threaded nipple 8=by which means thecasing I may be connected to a source of fluid under pressure (notshown) for instance, anv

automobile tire.

A block 9 may bev positioned. within. the end 5 of tube land may beprovided with a. relatively restricted aperture` lll. whichpermitscommunication between nipple 8V andthe interior of tube 4. A rod II maybe positioned Withinv casing` I; and may terminate at one end in pin I2of relatively restricted diameter, said pin` being adapted to carry cupwasher I3 maintained in desired position upon pin I2 by means of collarI4'` Washer I3 may be constructed of leather, rubber or other pliablematerial and may serve as a plunger against Which the fluid introducedthrough the restricted. aperture Ill may act. A coil spring I5 mayencircle rod I I, one end of said spring being adapted to abut againstwasher IB positioned. upon pin I2, immediately above cup washer I 3A. Asleeve Il may be loosely positioned upon rod' II and is adapted.tocontact the opposite end' of coil spring I5. In other. words, springI5 is conned upon. rod II between cup washer I3 andY sleeve I1.

A coilspring I8 may also encircle rodv II, oneA end ofpsaid springlabutting against` annular flange I-9.- of sleeve II. The open end ofibore 2v may be providedwith threads Zllfl which maybe adapted.- toengagewith cooperatingY threads: 2.I.-l 5;' provided upon the'exterior portionof one endi of cylindrical sleevef2-2-. The inner surface of sleeve 2.2'mayV be. provided with threads 23 which may' bey adapted to engage withcooperating threads carried uponthe surface of nut 24. may extend intobore: 2l and may be provided at its opposite end with annular flanger25V whichmaybe loosely positioned about sleeve Il... Spring, I8-, as canreadily be seen, is confined between flange IB and nut 24. f5;

A- member 26 may be positioned atfone end creasing I, said member being.provided Withthreads 2l which may be adapted toy engage threads 2B. uponthev endof. sleeve 22. Theimember. 26 may, throughout a major portion ofits length, be substantially semi-cylindrical and may be provided with.a, at face`28. Said member may also be providedwitha longitudinalAcentral aperture. 2'9.- whichl may be coaxially' positioned With respectto the bores 2 and 3 whereby rod I I, Whenmoved longitudinally withincasing I,.may extendl into` aperture. 29. The member 26.` being, ofsubstantially cylindrical construction has a longitudinal openingprovided along aperture. 2.9 whereby thepositionof the end of. rod- 30II, when. the samel is moved outwardly from casingl,.may` beobserved.The face 28. of member. 26. mayl be-rprovided. with a series-ofcalibrations 3l1 which may be designated in numerical units3I.` Y 35 Ifdesired, calibrations ('not shown)- may be. providedupon'that portion.ofrod II whichprojects from the body of the gauge and a datum point maybe indicatedv uponthe body ofthe gauge adjacent, the projectingrod. Inthis manner,.the degree Vof movement of` the rod' and hence the pressuremay be ascertained.

rIn measuringl fluidpressures throughout` a relatively wide range, itis. substantially impossible to.; use'a single; resisting' spring andobtain accurate results throughoutk the entire range of pressures. Inorder to. eliminate the cumulative, errors which are inherent in the useof aV single springthroughout a widerange of` pressures, plural spring.gauges have been constructedfwherein 50.`

a pluralityv of springs of different tensions or.y weights may besubjectedto thepressure of the iluidto be measured and are adaptedto actin seriesor sequentially. However, the. gauges of this characterhavebeenprovided witha plurality or 515i pressure chambers within each ofwhich one of said springs is adapted to operate. As a feature of ourinvention we may utilize the desirable features of a plural spring gaugeand yet provide but one pressure cylinder. In this manner theconstruction of the gauge is materially simplified and the cost of thedevice is reduced.

In operation, spring I5 may be of lesser strength or tension than springI8 and, as has been hereinbefore described, said springs are separatedby the sleeve I'l which is loosely positioned upon the rod II. In otherwords, sleeve II may be described as a floating connection between saidsprings. When iiuid under pressure is introduced through aperture I inblock 9, said uid acts upon cup washer I3 and tends to displace.

the same upwardly. Under normal no load conditions, both springs I5 andI8 may be under a relatively small amount of compression. Consequently,the force of the uid under pressure acting upon cup washer I3 initiallydisplaces rod II against the resistance of spring I5 since said springis the weaker of the two resisting members. During the initial movementsof rod II, spring I8 retains its original position and said rod movesupwardly through sleeve II. The initial or low pressure readings may beascertained by means of the position of end 32 of rod Il with respect tocalibrations 38. A collar 33 may be rigidly mounted upon rod I Iintermediate the distance between sleeve I'I and cup washer I3 when rodI I is in its normal or no load position. However, as rod I I movesupwardly due to the action of the uid pressure, spring I5 is compressedand collar 33 carried by said rod moves upwardly toward sleeve Il. Afterspring I5 has been compressed to a desirable degree, collar 33 contactsthe lower portion of sleeve Il and, consequently, a rigid connection isestablished between rod II and sleeve I1. If greater fluid pressures actupon cup washer I3, the movement of rod II is thereafter resisted byspring I8 and, consequently, the Upper range of pressures may be read bycorrelating the position of end 32 of rod II with respect tocalibrations 30.

It can readily be seen that the initial or low pressure readings aredependent upon the compression or resistance of spring I5 whereas theupper or higher pressure readings are dependent upon the compression ofspring I8. The maximum compression to which spring I5 may be subjected,may be determined or controlled by the position of collar 33 upon rod II. In this manner spring I8 may be brought into action at substantiallyany point throughout the range of the gauge at or previous to the totalcollapsing of spring I5.

Inasmuch as the normal or no load compression of spring I5 is dependentupon the distance.

between washer I6 and sleeve I'I, said compression may be varied bychanging the position of sleeve I'I with respect to said washer. Sincespring I8 is of greater weight or tension than spring I5, said heaverspring will, when both are normally compressed, overpower spring I5thereby maintaining sleeve II at the lowermost position within sleeve22. Consequently, by rotating sleeve 22 within casing I, said sleeve maybe raised or lowered, thereby raising or lowering sleeve I'l anddecreasing or increasing the normal or no load compression of spring I5.Similarly, the normal or no load compression of spring I8 is dependentupon the distance between sleeve I1 and nut 24. Hence, by rotating nut24, the same maybe raised or lowered with respect to sleeve 2,2 and theno load compression of spring I8 may be thereby decreased or increasedwithout disturbing the adjustment of spring I5.

It is to be understood, of course, that although my invention isdescribed in conjunction with a gauge having two springs and a singlecompression chamber, two or more springs may be used with but a singlecompression chamber, depending upon the pressure range for which thegauge is constructed and the accuracy desired. It is also to beunderstood that, any means may be utilized to correlate the movement ofthe indicator rod I I and the calibrated indicia, since the specificmeans shown and described is merely exemplary of one of many ways inwhich the same may be accomplished.

We claim as our invention:

l. A fluid pressure gauge comprising in combination, a tubular casing, arod positioned coaxially within said casing, a plunger upon one end ofsaid rod, means for applying fluid under pressure to one side of theplunger to move said rod, means for resisting the movement of said rodcomprising a plurality of springs of different tension sequentiallyoperating to resist movement of said rod, and means for independentlyadjusting the tension of said springs.

2. A fluid pressure gauge comprising in combination, a casing having asingle pressure chamber, an indicator rod positioned within saidpressure chamber, a plunger mounted upon one end of said rod, aplurality of coiled springs of different tension conned undercompression upon said rod, said springs being alined in an end to endrelation, a sleeve loosely positioned upon said rod between adjacentends of two springs, means whereby fluid under pressure may act uponsaid plunger to displace said rod, and xed means rigidly upon said rodfor contacting said sleeve after said rod has been displaced apredetermined distance.

3.`A uid pressure gauge comprising in combination, a casing having asingle pressure chamber, an indicator rod positioned within saidpressure chamber, a plunger mounted upon one end of said rod, aplurality of springs of different tensions conned under compression uponsaid rod, means whereby fluid under pressure may act upon said plungerto displace said rod, means upon said rod for compressing the lightestspring during l the initial predetermined portion of travel of theplunger, means associating the rod and a heavier spring at a subsequentportion of travel of the plunger, means for independently adjusting thetension of said springs, and means for interpolating effective movementof the rod in desired units.

4. A iiuid pressure gauge comprising in combination, a tubular casing,an indicator rod movably positioned within said casing, a plungercarried at one end of said rod, means whereby iiuid under pressure mayact upon said plunger to displace said rod, means associated with saidrod for resisting displacement thereof comprising a plurality ofnormally compressed coil springs of different tension, a sleeve looselypositioned upon said rod between the ends of adjacent springs, meansupon said rod for contacting said sleeve when said rod has moved apredetermined distance against the tension of the weakest spring wherebyfurther movement of said rod is resisted by the adjacent strongerspring, .and means for independently adjusting the initial compressionof each spring.

GEORGE E. FARLEY. FREDERICK A. KOESTER.

